When is the content of the kernel ring buffer reset?

The content of the kernel ring buffer can be reset explicitly by using the command dmesg with the --clear option. This action clears the kernel ring buffer, allowing for the collection of new messages without old entries mixed in. The ring buffer is a circular buffer used by the Linux kernel to store log messages, and clearing it can be particularly useful for debugging or monitoring purposes, giving you a fresh view of recent events.

The other answers do not accurately describe events that would result in the kernel ring buffer being reset. Reading from the buffer with the dmesg command does not clear it; it simply displays its current contents. There is no built-in timer or mechanism that resets the buffer based on elapsed time, nor does loading or unloading kernel modules trigger a reset of the buffer contents. Thus, the correct action to reset the kernel ring buffer is indeed the explicit use of the dmesg --clear command.